1. Technical Field
This invention relates generally to rotary shaft seals, and more particularly to methods of fabricating PTFE seal elements and a rotary shaft seal assembly having a PTFE seal element.
2. Related Art
Rotary shaft seal assemblies are known to incorporate PTFE seal elements for establishing a low friction seal relative to a rotating shaft. An understood challenge in manufacturing these seal assemblies is establishing a reliable bond between the PTFE seal element and the adjoining substrate of the seal assembly. The properties of PTFE, being lubricious, typically makes it difficult to form a reliable bond between it and the adjoining substrate. In one known method of fabricating a PTFE seal assembly, a PTFE seal element is first machined from a PTFE billet, and then the PTFE seal element is further processed in a secondary operation using a “wet-chemistry” process to etch and chemically modify a surface of the PTFE seal element. The chemically modified PTFE element is then molded to a substrate of the seal assembly. Although this process can prove effective in attaining a bond between the PTFE element and the adjoining seal assembly substrate, it is potentially hazardous given the wet-chemistry process used to chemically modify the PTFE element. In addition to the wet-chemistry process being potentially hazardous, it is not a practiced by many suppliers, and thus, the number of potential sources capable of performing the process is limited. As such, with the wet-chemistry process being potentially hazardous and offered by limited suppliers, the costs associated with this process are typically high. Accordingly, the total manufacturing cost of the PTFE seal assembly is increased.